The biggest piece of environmental legislation in decades -- the Omnibus Public Lands Management Act of 2009 -- might have been "of 2008," or been passed in various forms even earlier, were it not for Oklahoma Republican Sen. Tom Coburn.

The Omnibus Act bundled 164 conservation efforts into a massive package that designated 2 million acres of new wilderness and increased the wild and scenic river system by 50 percent. It helped enable buyouts of oil and gas leases in Wyoming's Bridger-Teton National Forest and ratified wilderness deals that were negotiated on the ground in Idaho's Owyhee County and Utah's Washington County. Many Western environmentalists, ranchers, county officials and other stakeholders were involved in creating the Omnibus.

But the act itself can be blamed on Coburn, which is why it's known around Capitol Hill as "Tomnibus." "What he did was put holds on virtually every bill that came out of the Senate Energy and Natural Resources Committee," says Paul Spitler, a high-ranking Wilderness Society staffer based in Washington, D.C. Coburn blocked so many individual bills in 2008 that supporters decided to lump them together into the omnibus package in early 2009, hoping to pass all 164 measures at once. They succeeded, but not without a fight.

At Coburn's insistence, the Omnibus Act was "read (on the Senate floor) until the wee hours of the morning, which dragged out the timeline for an extra day," says Spitler. "And at that point, he said, ‘OK, you guys can go home now.' "

Coburn again drew the ire of Western environmentalists in September, by holding up passage of five popular wildlife-protection bills, one of which -- the Crane Conservation Act -- was sponsored by a fellow Republican, Idaho Sen. Mike Crapo. Oregon's Sen. Jeff Merkley, California's Sen. Barbara Boxer and Washington's Sen. Maria Cantwell -- all Western Democrats -- were also among the five bills' sponsors. Probably the most popular one would have banned the "animal crush videos" that Wayne Pacelle, head of the Humane Society of the United States, describes as "the vile depictions of staged scenes in which scantily clad women maim and torture animals for the sexual gratification of viewers." Coburn said those bills were a distraction at a time when the Senate should be addressing the deficit.

"One can understand Sen. Coburn's interest in fiscal restraint," Pacelle wrote in his Humane Society blog. "But in his case, it is an obsession, and it borders on a mania."

Stories like this justify Coburn's nickname, which plays off his medical degree and the name of the villain in an old James Bond movie: "Dr. No." And "No" might as well be the middle name of Oklahoma's other ultraconservative senator, James Mountain Inhofe. Both have used their Senate tenures largely for one purpose: Obstruction. They're effective advocates for the causes they believe in, slowing or stopping legislation and regulations they oppose. They've also attracted national attention by taking contrarian, often-controversial stances, and by giving a prominent voice to beliefs that are far out of the mainstream. They help give extremism credibility.

Inhofe has spent much of his career working to undermine or totally dismantle environmental protections. As chairman of the Senate Environment and Public Works Committee from 2003 to early 2007, he often held hearings that were more like kangaroo courts. In one 2003 hearing on climate change, he pitted two climate-change deniers against one scientist representing the mainstream view. That summer he held a similarly biased hearing on mercury pollution: A lone voice expressed the majority view that mercury is toxic and regulations are needed on the power plants that release 48 tons of airborne mercury every year, while two experts testified in favor of the opposite view. The Bush administration subsequently moved to dramatically weaken Clinton-era mercury regulations, a rollback later defeated in federal court.

Inhofe also opposes efforts to protect polar bears by limiting the carbon emissions that cause climate change, denouncing them as "an attack on our economy and our energy security." As a leading climate-change denier, he's worked to block any significant action on the problem, including the environmentalists' best hope -- the cap-and-trade bill that died earlier this year -- even as climate change threatens the West, contributing to drought, a forest beetle crisis and record-breaking wildfires.

Inhofe saves some of his hottest rage for the Environmental Protection Agency, which he's called "a Gestapo bureaucracy." In 2006, when EPA staffers based in Denver went into natural gas fields with infra-red cameras to detect pollution, Inhofe attacked the agency and tried to pressure the employees to back off. In 2009, he called for a criminal investigation into the EPA, charging it with suppressing evidence that climate change doesn't amount to much. "They've been cooking that science since 1998," he told Fox News.

"He seems to really have a long-term vendetta against the EPA," says Scott Thomasson, domestic policy director for the Progressive Policy Institute, a moderate left-of-center think tank. "(It's) so deeply ingrained at this point that he has a presumption of incompetence and malice about everything that they do."

Meanwhile, Coburn, a longtime friend of the National Rifle Association, used legislative trickery to make it legal to carry loaded guns in national parks, despite the strong opposition of the National Park Service. He slipped the amendment into the Credit Cardholders' Bill of Rights Act of 2009.

Earlier this year, Coburn blocked Senate approval of a $3.4 billion payment to Native Americans to settle a class-action lawsuit over the Department of Interior's longtime mismanagement of mineral royalties on tribal lands. (That case is not yet settled.) In 2009, he tried to block Senate confirmation of Hilary Tompkins, a Stanford-educated New Mexico Navajo, as the top lawyer in Obama's Interior Department. (The Senate eventually confirmed Tompkins.) In 2008, he opposed a sweeping $35 billion improvement of the Indian Health Service, even though many Western senators of both parties backed it and a total of 83 senators voted for it.

Both of the Oklahoma senators strongly support the oil and gas industry. They've repeatedly backed federal subsidies and sought to increase drilling, including in the Arctic National Wildlife Refuge, while resisting tougher regulations, fuel efficiency and conservation measures. Inhofe led the fight to carve out an exemption in the Safe Drinking Water Act for "fracking" -- the high-pressure pumping of chemicals to free up natural gas in underground formations, a process many Westerners believe threatens water quality. This theme of the senators' influence is felt every day in Western states where drillers are constantly claiming more of the landscape.

According to the League of Conservation Voters, during his terms in the U.S. Senate and House, Coburn has voted against environmentalists' positions from 87 to 100 percent of the time, depending on which session you focus on. Inhofe has voted against environmentalists 96 to 100 percent of the time. That's another way the Oklahoma "nos" are heard around the West.